Second City is back in second place, at least when it comes to height. New York's One World Trade Center will officially open next year as America's tallest building, topping Chicago's Willis Tower by 325 feet (99 meters).

The Chicago-based council—an international organization that measures skyscrapers and arbitrates height records—defines a spire as a "vertical element that completes the architectural expression of the building and is intended as permanent." By contrast, antennas, flagpoles, and signage are considered "functional-technical equipment subject to change."

Translation: The 408-foot (124-meter) needle is part of One World Trade Center's architectural height of 1,776 feet (541 meters). The Willis (formerly Sears) Tower, America's tallest building for the past 40 years, stands a "mere" 1,451 feet (442 meters) tall.

To better understand the council and its criteria, we sat down with Timothy Johnson, the council's chair and a design partner at the firm NBBJ.

People may be surprised to learn there's an organization that certifies building heights. How long has the council been around?

The council was started in 1969 by Lynn Beedle, a structural-engineering professor at Lehigh University. He and [Willis Tower designer] Fazlur Khan, a structural engineer and professor at [the Illinois Institute of Technology], brought this group together because a lot of tall buildings were being designed and erected in the Chicago area and around the U.S. It was such a new topic then, and they wanted to disseminate [accurate] information to the country and the world at large.

These two gentlemen were both academics and professionals—very connected in the world. So we very quickly became a global organization, and conferences began happening all over the world wherever there were tall buildings.

The council's height committee made this determination about One World Trade Center. Who's on that committee, and how does it work?

It's multidisciplinary. There are architects, engineers, contractors, developers, academics, specialty consultants, suppliers—the same demographic as the rest of our organization. The height committee is the highest level of leadership we have: our board of trustees, our global advisory group, and a few [other experts] we handpicked. At this last meeting, we had 25 people representing 13 different countries and 19 cities.

Is there an agreed-upon standard—a working definition of "tall building"?

The simplest way to put it is that you need vertical transportation to get around it. But it's hard to give a technical answer. We've never said, "A building has to be at least 70 stories" or something like that.

But we don't just look at building height. Part of our name concerns urban habitat. We want to know: How do tall buildings become part of the cityscape? And how does that become part of solving some of the population-expansion challenges we have today?

The council has three criteria for measuring building height. What are they?

One is that we evaluate the highest occupied floor—how high you can put people above the face of the Earth. [Another is that we] evaluate height to the tip of the building.

But to us the most significant one—the one that determines how we'll keep the record books and how we'll rate the buildings—is the architectural height. To explain this, I always point to the difference between the Chrysler Building and the Empire State Building. The spire on top of the Chrysler is absolutely integral to the [architectural] concept of the building. But the Empire State Building has a cylindrical round drum at the top with an antenna [and other things that aren't] integral.

Some [have suggested that] the criteria should be bulk. But we're not a group that wants to promote "big." The Willis Tower is still the biggest vertical building in the county. And One World Trade is relatively small compared to a lot of buildings. In our last quarterly, we did an issue on vanity height—height for height's sake. That created a lot of controversy, which we like: We're not a group that's biased in one way or the other. The key is that, with things like sustainability and carbon footprint, we want people to use as much of the building as they can—to maximize these buildings.

In New York, some of the tallest buildings being built right now are residential, because that's where the economy is. It's not all tall office buildings like it was 20 years ago. And those residential buildings are very slender.

How do you verify that an architect's figure is actually correct?

Honestly, we have to take their word for it. It's a licensed profession, so the final construction documents that we evaluate are legal tender documents. The building has to be built to those specifications.

Someone asked me whether we measured [One World Trade Center] from the sidewalk to the top—implying that we had a 1,776-foot-long tape measure!

So no one risks life and limb taking the physical measure of a building?

No, that doesn't happen. There's probably a way we could use Newtonian physics and a laser-guided compass to get an exact measurement. But the element we use as a consistent measuring device are the record documents.

Chicago's mayor wasn't too happy about the council's ruling. Why do you think people care so much about which city has the tallest building?

The council is based in Chicago, but we weren't influenced by any [local sentiment or hometown bias]. Still, I get a very strong drift, from what's come out so far in the press, that the rivalry between Chicago and New York is the real story here.

I think that's all healthy and good. We know that man's greatest achievements are cities, and the way that a lot of cities are identified is by their tallest building. And the U.S. and Chicago, where the skyscraper was born [the Home Insurance Building in Chicago, designed by architect William Le Baron Jenney in 1855 at 180 feet (55 meters) tall], enjoyed for many, many years the Sears Tower being the tallest building in the Western Hemisphere.

It was probably more painful to Chicago when they lost the tallest building in the world to Asia—when they handed that title over to [Malaysia's] Petronas Towers [in 1996]. That was a big blow, not just to Chicago but to the whole U.S., which had held the tallest-building record from the beginning.

It's probably no consolation to Chicagoans, but no one [who designed and built] One World Trade Center ever said, "We want to build a building that's taller than the Willis Tower." The vision of the master planner, Daniel Libeskind, was to build it 1,776 feet tall, because [that figure represents] independence, democracy, freedom.

So I see this as a public-interest story with two stories: One is about 1,776, which relates to the 9/11 attack, and the other is this rivalry between the two cities. Our height committee never thought, "We have to make this judgment to determine the tallest building in the country." We just had to confirm whether it was 1,776 feet.

What's important to me is that this may never happen again in the U.S. We just don't have the same demand for tall buildings that other places in the world do. A lot of Chinese developers are starting to come to the U.S. who have built the tallest buildings in their particular cities. And they may want to make a statement here—to say, "We're a Chinese company and we've just built the tallest building in the U.S." So maybe I shouldn't say it'll never happen. It might just as well happen, for reasons that frankly don't make sense to us.

Where does One World Trade Center rank in terms of the world's tallest buildings?

Well, the caveat is that One World Trade Center is still technically not complete in our book. It has to be occupied, have its certificate of occupancy, and then it'll be recorded in our books as officially 1,776 feet tall.

Right now it's the third-tallest building in the world. The second-tallest is the Makkah Royal Clock Tower in Mecca, Saudi Arabia [1,972 feet, 601 meters].

And the tallest is the Burj Khalifa in Dubai [2,717 feet, 828 meters]. Willis Tower is currently in tenth place.

But there's a building in Shanghai—the Shanghai Tower—that will probably jump into the second position around the time One World Trade Center is completed. And there's one in Shenzhen—called Ping An Finance Center—also under construction. And there's another one under construction in Jeddah, Saudi Arabia—called the Kingdom Tower—which is set to be completed at one kilometer (1,000 meters).

So right now there are three more, though the one is Shanghai [is the only one close to completion]. When World Trade One Center is ratified into our records next year, there might be one tower in front of it. In the next three to four years there'll probably be two towers in front of it.

Although not widely publicised, by 2019 the worlds tallest building will be the 2,887 foot or 880 metre high Manningham Priestly Tower in Bradford, England. The blue and purple building is described by it's Manchester based architects Pace Miller and Grove as Art Nouveau turned on it's head. The foundations of the structure are already in-situ and when complete will be the only man made structure in the United Kingdom to be seen from both the East and West coasts.